Eight players, four from the American League, four from the National League

Selected and invited by Major League Baseball

Format (Three rounds)

Round One
Eight hitters
Each player gets 10 outs per at bat
Top four advance to Round Two (regardless of League affiliation)

Round Two
Four hitters
Home runs from Round One do not carry over to Round Two
Each player gets 10 out per at bat
Hitters will be seeded 1 through 4, based upon HR total in Round One

First semi-final: 2-seed vs. 3-seed

Second semi-final: 1-seed vs. 4-seed
Winners of the two semi-finals advance to the Championship Round

The Championship Round
Two hitters
Each player gets 10 outs per at bat
Most home runs in finals is Champion

Rules

An out is registered when a player swings at a pitch and does not hit a home run. A ball hit over the fence must be fair to count as a home run.

Since a home run does not count as an out, an infinite number of home runs is possible.

2001 Century 21 Home Run DerbyDetailed format

Round One

Eight hitters (four AL, four NL)

Each player gets 10 outs per at bat

Four hitters with highest number of home runs in Round One advance to Round Two (regardless of League affiliation)

TIEBREAKER: If a tie exists among players for advancement into Round Two, the following tie-breakers will be used:

Tie-breaker #1: regular season home run total at All-Star break
Tie breaker #2: distance of longest home run in Round One

Round Two

Four hitters advance from Round One

Each player gets 10 outs per at bat

Two hitters with highest number of home runs in Round Two advance to Championship Round (regardless of League affiliation)

TIEBREAKER: If a tie exists among players for advancement into Championship Round, the following tie-breakers will be used:

Tie-breaker #1: most home runs in Round One (therefore most through two rounds)
Tie-breaker #2: regular season home run total at All-Star break
Tie breaker #3: distance of longest home run in Round One or Round Two

The Championship Round

Two hitters advance from Round Two

Each player gets 10 outs per at bat

Champion will be the player with the most home runs in the Championship Round

TIEBREAKER: If the two finalists hit the same number of home runs in The Championship Round, the Home Run Derby will go into "HOME RUN DERBY SHOWDOWN". Rules are noted below:

Players will hit in the same order they hit in Championship Round

Each player will get one swing

If one player hits a home run and the other makes an out, the player who hits the home run is the Champion

If they both make an out or both hit a home run, the process will be repeated until one player hits a home run and the other makes an out